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N-hydroxyphthalimide-TiO2 complex visible light photocatalysis
摘要： TiO2 is the most established semiconductor photocatalyst. The prominence of TiO2 is becoming increasingly obvious because its interfacial redox reactions have implication on a wide range processes such as energy conversion and environmental remediation. Herein, we exploited the surface complex created by the interaction between organic molecules with binding sites and accommodating surface of TiO2 for visible light-driven selective aerobic oxidation reactions. A novel surface complex formed between N-hydroxyphthalimide (NHPI) and TiO2 was discovered. The NHPI-TiO2 complex turned out to be an outstanding visible light photocatalyst and was successfully used in the selective oxidation of amines into imines with atmosphere O2 under blue LED irradiation. The stability of the NHPI-TiO2 complex was preserved by 3 mol% of (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) acted as a cooperative catalyst. Moreover, selectivities for the imine products were also prompted by TEMPO. Superoxide radicals (O2?-) were evidenced to be the primary reactive oxygen species (ROS) to execute the oxidative conversions. This work suggests that TiO2 surface complexes can be robust photocatalysts for visible light-driven selective aerobic reactions, provided that an appropriate cooperative redox catalyst exists to channel the photocatalytic electron transfer.
关键词： titanium dioxide,surface complex,N-hydroxyphthalimide,molecular oxygen,TEMPO
更新于2025-09-23 15:22:29
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An efficient visible-light-responsive surface charge transfer complex AA-TiO2 based dye-sensitized solar cell
摘要： This work investigated a new strategy for visible light responsive dye-sensitized solar cell: the ligand-to-metal charge transfer (LMCT) takes place between TiO2 nanoparticles and ascorbic acid (AA). The surface LMCT complex AA-TiO2 extended the spectral responsive range to 800 nm and exhibited prominent visible light activity, enhancing utilization of the solar spectrum. The optimal photovoltaic conversion efficiency of the visible-light-responsive AA-TiO2 based dye-sensitized solar cell reach value of 3.50%. The low-cost, non-toxic and environment friendly surface adsorbate AA will demonstrate a feasible approach for replacing the most common used ruthenium complex dyes, thereby offering a strategy for development of low-cost and high efficiency DSSCs.
关键词： Dye-sensitized solar cell,Surface complex,Ligand-to-metal charge transfer (LMCT),Ascorbic acid,Visible light activity
更新于2025-09-23 15:19:57
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Surface Complexation for Photocatalytic Organic Transformations
摘要： Photocatalysis constitutes an important research interest due to its capability for achieving important chemical reactions in an environmentally green and sustainable manner. The use of heterogeneous photocatalysts adds additional advantages such as ease of separation from reaction mixtures, reusability, as well as photo, thermal and chemical stability. In this account, we showed how the surface complexation of different key players on TiO2 can be used control the reaction pathway to enable difficult organic transformations, as demonstrated by the selective aerobic oxidation of sulfides to sulfoxides. First, we designed a photocatalytic-surface complexation system comprising three fundamental components; visible-light-absorbing dye, TiO2 and TEMPO as the redox mediator. Next, the said system was elegantly simplified into a visible-light-harvesting surface complex generated in-situ between TiO2 and tertiary amines, which enables O2 to be selectively activated only in the presence of the target sulfide substrate. This was then expanded into the new concept of synergistic photocatalysis, which is based on the interplay of reactants (sulfides and benzylamines) via the aforementioned visible-light-harvesting surface complex to enable two seemingly irrelevant reactions in one photocatalytic system. Lastly, we briefly discussed how surface complexation on heterogeneous catalysts such as metal oxides can be further utilized for photocatalytic organic transformations.
关键词： Surface complex,Redox Mediator,Photocatalysis
更新于2025-09-10 09:29:36
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Salicylic acid complexed with TiO2 for visible light-driven selective oxidation of amines into imines with air
摘要： The interplay of salicylic acid (SA) and reactive oxygen species (ROS) can modulate biotic and abiotic stress of plants, essential biological aerobic oxidation processes. Meanwhile, ROS plays a critical role in TiO2 photocatalytic system for the degradation of organic species. Herein, we developed a system consisted of SA and TiO2 aiming at the selective oxidation of organic molecules by ROS. Interestingly, SA complexed with TiO2 leads to ligand-to-metal charge transfer (LMCT) under visible light irradiation. The charge transfer from ligand (chemically adsorbed SA) to metal (conduction band of TiO2) activates O2 to ROS, superoxide (O2?). The positive charge located at ligand SA is connected with (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) catalysis for direct two-electron oxidation of amines and later regenerated by O2. SA and its derivatives were screened as ligands of TiO2 for the selective aerobic oxidation of amines into imines under blue light-emitting diode (LED) irradiation in which 5-CH3O-SA (5-methoxysalicylic acid, 0.8 mol%) complexed with anatase TiO2 and coupled with TEMPO (5 mol%) confers significantly better results than the others. By this visible light LMCT route, both primary amines and secondary amines can be selectively oxidized into corresponding imines with atmosphere O2 as the terminal oxidant. Importantly, the desired product of N-benzylidenebenzylamine can be isolated in 92% yield.
关键词： Salicylic acid,Titanium dioxide,Amines,Photocatalysis,Surface complex
更新于2025-09-04 15:30:14